Traditionally, fluids have been processed in systems that utilize stainless steel containers. These containers are sterilized after use so that they can be reused. The sterilization procedures are expensive and cumbersome as well as being ineffectual at times.
In order to provide greater flexibility in manufacturing and reduce the time needed to effect a valid regeneration of the equipment, manufacturers have begun to utilize disposable sterilized bags that are used once with a product batch and then disposed.
An example of use of these disposable bags is in a system for mixing two or more ingredients, at least one of which is liquid and the other(s) being liquid or solid and the bag has a means for causing the ingredients to mix as uniformly as possible.
For example, in the production of vaccines, the liquids involved often contain aluminum salt as an adjuvant. The aluminum salt improves the effectiveness of the vaccine by enhancing the body's immune response. Unfortunately, the aluminum salt has particles sizes larger than 0.2 μm, and thus sterile filtering generally is not an option. As a result, it is often advantageous to minimize the number of containers into which the vaccine needs to be transferred, since each transfer represents a potential breach of sterility, and the resulting contamination can't be filtered away. Accordingly, it is advantageous to be able to mix vaccines in the same container, such as a flexible, disposable bag, that they are shipped in.
Another example is a bioreactor or fermentor in which cells are either in suspension or on microcarriers and the bag has a means for circulating the liquid, gases and in some cases the cells around the interior of the bag.
Most conventional mixing bags are shaped like cylinders, with the bottom of the bag forming a cone, to mimic the shape of the tanks that the disposable bags are replacing. Although this shape is conducive to mixing the contents of the bag, it is not conducive to shipping and storage.
Other conventional mixing bags are shaped like cubes. The cube shape is conducive to shipping and storage, but is not a good shape for mixing, as the corners of the cube easily can become dead spots where mixing is impeded.
Typically, the means for mixing or circulating is a magnetically coupled impeller contained within the bag and a magnetic motor outside the bag which remotely causes the impeller to spin. However, a problem with such 2D mixing bags is that the impellers of the mixer can contact and damage the opposing face of the bag, such as when the fluid level becomes low, or during initial shipment when the bag contains no fluid.
It therefore would be desirable to provide a disposable, preferably deformable, container for fluids having means for minimizing or preventing foaming at the container inlet and at the container outlet, that includes a mixing device that will not damage the container even when the liquid level in the container is low or the container is empty. In addition, it would be desirable to provide such a container wherein fluid entering the inlet is directed away from the outlet thereby to effect mixing of the incoming fluid with the fluid in the container.